These humanoids have flesh that resembles a peeled orange or other citrus fruit: semi-translucent with prominent veins. Brightly colored, some Rutaceaens are orange, some are yellow, and some green. They prefer warm climates with lots of rainfall.
It is traditional for two warlike countries to each give their first-born royal prince as a hostage to each other to prevent war. One of the princes has been murdered, and the PCs have a few days to rescue the prince in the other country to save him from being executed and a bloodthirsty war from breaking out.